An earlier International patent application published under serial number WO89/09898 describes a vehicle transmission in which the change over between two regimes, corresponding to the two regimes described above, may be a shockless synchronous change, there being no change in overall transmission ratio during the change in regimes, and the transmission is considerably simplified over earlier vehicle transmission systems, avoiding the use of parallel transmission paths between the power recirculation system and the output transmission member and the consequent necessity of a change in transmission path within the first regime.
The transmission is arranged such that when the first or "low" regime provides a maximum forward speed, the ratio of the variator is at its maximum reduction and this corresponds to the minimum forward speed provided in the "high" regime. A change over between regimes under these circumstances is a shockless synchronous change. Only simple declutching and clutching operations are required for the change over and, where clutches are provided in both the transmission path directly from the output member of the variator to the output transmission member (such as the output shaft) and in the transmission path between the power recirculation system and the said output transmission member, both clutches could be engaged during the change over between regimes.